[POWERPC] Enable the RTAS udbg console on IBM Cell Blade

Enable the RTAS udbg console on IBM Cell Blade, this allows xmon
to work.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/platforms/cell/setup.c b/arch/powerpc/platforms/cell/setup.c
index 2436eaa..00d112f 100644
--- a/arch/powerpc/platforms/cell/setup.c
+++ b/arch/powerpc/platforms/cell/setup.c
@@ -141,6 +141,10 @@
 	    !of_flat_dt_is_compatible(root, "IBM,CPBW-1.0"))
 		return 0;
 
+#ifdef CONFIG_UDBG_RTAS_CONSOLE
+	udbg_init_rtas_console();
+#endif
+
 	hpte_init_native();
 
 	return 1;